If you are traveling to a place with limits for extra checked bags, you can check a box instead. The box can weigh up to 50 pounds (23 kilograms). The total length + width + height of the box must be less than 62 inches (158 centimeters).

Yes, you can check a cardboard box as luggage on United Airlines, provided it meets the standard size and weight requirements for checked bags. In 2026, the box must not exceed 62 linear inches (length + width + height) and must weigh less than 50 pounds (23 kg) for most economy passengers to avoid heavy oversize or overweight fees. The box must be sturdy, securely sealed with heavy-duty packing tape, and free of any hazardous material markings or old shipping labels. United specifically requires that the box be "factory-sealed" or professional-grade to prevent bursting in the pressurized cargo hold. It is important to note that United often applies a "limited liability release" to checked boxes, meaning if the box is crushed or the contents are damaged during transit, the airline may not provide compensation. To protect your items, many travelers "shrink-wrap" their boxes at the airport for an extra layer of durability and weatherproofing before handing them over at the check-in counter.